Archive for the ‘Green Energy News’ Category

From laptops to smartphones to the burgeoning electric car industry, our world is increasingly reliant on rechargeable batteries. But as anyone who’s owned a laptop for more than a few years knows, batteries eventually lose their ability to hold a full charge.

Scientists never really understood why this happens, which has made it a hard problem to fix. But according to a pair of recent studies by researchers from the U.S. Department of Energy, published in the journal Nature Communications, we may be closer than ever to a battery that doesn’t degrade.

Working specifically with lithium-ion batteries, commonly used in consumer devices because of their light weight and high capacity, the scientists have mapped the charge and discharge process down to billionths of a meter to better understand exactly how degradation works. They discovered two culprits in battery degradation. The first: microscopic vulnerabilities in the structure of the battery material steer the lithium ions haphazardly through the cell, eroding the battery in seemingly random ways, much like rust spreads across imperfections in steel. In the second study, focused on finding the best balance between voltage, storage capacity and maximum charge cycles, researchers not only found similar issues with the ion flow, but also tiny accumulations of nano-scale crystals left behind by chemical reactions, which cause the flow of ions to become even more irregular after each charge. Running batteries at higher voltagesalso led to more ion path irregularities, and thus a more rapidly deteriorating battery.

It may seem like scientists should have fully understood the battery—a technology that’s effectively been around since 1800—decades ago. But Huolin Xin, a materials scientist at Brookhaven Lab and coauthor on both studies, says the winning combination of new technologies only recently became available.

“Many state-of-the-art characterization tools, such as aberration-corrected electron microscopes and new synchrotron X-ray techniques, were not available 10 years ago,” Xin says. But now, he says, they can be applied to the study of lithium-ion batteries.

The new data gives researchers a clearer picture of the how these batteries work, which could lead to longer-lasting batteries in consumer electronics in the not-too-distant future. But, it also presents new problems. Xin says maximizing surface area is important to battery performance, but a larger surface area also likely facilitates degradation.

“To prevent [surface degradation], we can either coat the cathode with a protection layer,” Xin says, “or hide these surfaces by creating boundaries within the micron-sized powders [inside the cell].”

Finding the most efficient, cost-effective ways to do this will be part of a future phase of the research.

But Daniel Abraham, a scientist focused on lithium-ion battery research at the Argonne National Laboratory outside Chicago, is skeptical that the new studies represent a real breakthrough. He says mapping work with similar materials has been done in the past, including by his team about 12 years ago. He also believes there may be more to battery degradation than what the new studies have found.

“They’re trying to make a correlation between performance degradation and the pictures that they see, which may not be correct,” Abraham says. “It’s partially the story, but I don’t think it’s the entire story.”

Xin, is more optimistic that the work will lead to battery improvements, not only for future electric vehicles, but for portable electronics as well.

“Lithium-nickel-manganese-cobalt-oxide cathode has recently been identified as the only commercially viable material for next-generation lithium-ion batteries,” Xin says. “By resolving its degradation problem, we can make next-generation batteries smaller and make them charge and discharge more reliably.”

The two battery experts do agree though, that for many important future applications, finding a way to make batteries that don’t wear out as quickly is just as important as creating batteries that have a greater capacity.

Xin points out that electric car buyers justifiably worry about battery failure after their warranty expires. Abraham notes that while you likely only need a couple of years of performance from your smartphone or tablet battery, for electric vehicles, most owners are looking for a battery that lasts 10 to 15 years. And for use in the electric grid (to store excess energy produced on off-peak hours), batteries should last 30 years or more.

That makes building a better battery for your laptop a lot easier than solving longevity problems in other areas.

“It’s good to have a higher energy density, but if you get a high energy density but not a long life, then the commercial viability of those technologies comes into question,” Abraham says. “Whereas, if you can show that you have a new technology and it can last between two and 30 years, that becomes immediately viable commercially.”

While the work of Xin and his colleagues may help researchers create batteries that don’t degrade as quickly, it’s clear that further breakthroughs will be necessary before we’ll see rechargeable batteries that last a decade or more without serious wear.

Scientists at Johannes Gutenberg University Mainz (JGU) have come out with positive news about increased efficiency of thin-film solar cells. As we know that scientists are trying to increase the efficiency of the solar cells so that they can be considered as serious alternative to the fossil fuels. Researchers at Johannes Gutenberg University Mainz (JGU) too are working at this angle. They opted for the computer simulations to probe deeper into the indium/gallium combination to increase the efficiency of Copper indium gallium (di)selenide (CIGS) thin-film solar cells. Till now CIGS has shown only about 20% efficiency though theoretically they can attain the efficiency levels of 30%.

Advantages of CIGS:
CIGS cells are cheaper than their counterpart silicon cells due to lower material and fabrication costs resulting in lowered manufacturing costs. CIGS has direct band-gap material therefore they exhibit a very strong light absorption tendency, and only 1-2 micrometers of CIGS is enough to absorb most of the sunlight. Conventional silicon photovoltaic cells are rigid but CIGS cells are flexible. Thin-film solar cells are slowly topping the popularity chart of solar market.

Working on the Efficiency of CIGS: Currently CIGS cells are showing efficiency of around 20%. These cells absorb sunlight through a thin layer made of copper, indium, gallium, selenium, and sulphur. The scientists at Mainz University headed by Professor Dr Claudia Felser are exploiting the computer simulations to find out the properties of CIGS. This research is a part of the comCIGS project. This project is financed by the Federal German Ministry for the Environment, Nature Conservation, and Nuclear Safety (BMU). The researchers are concentrating on the optimum proportion of indium/gallium puzzle. What ratio of indium/gallium would be ideal to increase the efficiency of CIGS? It was discovered earlier that the desired ratio should be 30:70, in practice; the highest efficiency level has been obtained with the exactly opposite ratio of 70:30.

Christian Ludwig who is the member of the Professor Felser’s team worked on the calculations using a hybrid method. This hybrid method included a combination of density functional calculations and Monte Carlo simulations. Dr Thomas Gruhn is the head of the theory group in the Prof. Felser’s team. He says, “Density functional calculations make it possible to assess the energies of local structures from the quantum mechanical point of view. The results can be used to determine temperature effects over wide length scale ranges with the help of Monte-Carlo simulations.”

Homogeneity of the material is the key to high efficiency:
Scientists find out that the indium and gallium atoms are not distributed evenly in the CIGS material; there is a phase when indium and gallium are completely separate. This separation happens at just below room temperature. Researchers also tried out various combinations of temperatures and discovered that the higher the temperature, the more homogeneous the material becomes. The more the lack of homogeneity of the gallium-rich material the lower the efficiency levels of gallium-rich CIGS cells. This phenomenon is discovered for the first time by Prof Felser’s team. The team also discovered a better way to manufacture CIGS solar cells. The research team says if gallium rich material is produced at higher temperatures, the material is notably more homogeneous. For maintaining the homogeneity, the gallium rich material should be cooled down rapidly.

Glass is used as substrate for solar cells. Glass has always restricted process temperatures. But Schott AG has been successful in inventing a special glass with which the process temperature can be increased. Naturally the cells would be more homogeneous. This would lead to the production of cells with a much greater efficiency level. Gruhn says, “We are currently working on large-format solar cells which should outperform conventional cells in terms of efficiency. The prospects look promising.”

Nanyang Technological University (NTU) recently announced it will be building a hybrid microgrid which will integrate multiple large-scale renewable energy sources.

The first in the region, the hybrid microgrid will test and demonstrate the integration of solar, wind, tidal-current, diesel, storage and power-to-gas technologies, and ensure these energy sources operate well together.

To be built under the new Renewable Energy Integration Demonstrator – Singapore (REIDS) initiative, the hybrid microgrid will be located offshore at Semakau Landfill and is expected to produce power in the megawatt (MW) range, which will be suitable for small islands, isolated villages, and emergency power supplies. It will be able to power around 250 HDB 4-room apartments, which together consume a peak of 1 MW.

This initiative is supported by the Singapore Economic Development Board (EDB), and the National Environment Agency (NEA). The S$8 million initial microgrid infrastructure will also facilitate the development and commercialization of energy technologies suited for tropical conditions to be developed by NTU together with 10 world leading companies.

“Sustainability is one of the major pillars of NTU’s research. We have been very active in clean energy research such as in tidal, solar and wind technologies and this new initiative will allow us to apply our research and integrate the different energy sources. In so doing, we hope to develop practical renewable solutions for the energy integration industry,” said NTU President Professor Bertil Andersson.

The initiative is expected to attract $20 million worth of projects over the next five years, in addition to the initial $8 million investment in infrastructure on the Semakau Landfill.

“NTU’s REIDS will serve as a strategic living lab for Singapore, encompassing a large scale microgrid with a plug-and-play setup that clean energy industry leaders can leverage to develop and demonstrate and diverse range of clean energy technologies,” said EDB’s Assistant Managing Director Mr Lim Kok Kiang.

The REIDS project is to be implemented in two phases. In the first phase, a microgrid facility will be built at the Semakau Landfill that will oversee energy storage facilities, solar photovoltaic panels and wind turbines. The hybrid microgrid will be designed to provide a full-scale test-bed for Singapore’s on-going energy research, working closely with scientists and engineers from both the public and private sectors.

A key problem posed by renewable energy sources is that of intermittent power supply. According to NTU, the hybrid microgrid aims to ensure a stable and consistent power supply through the integration of a variety of smart energy management and storage systems.

The second phase of the project will involve the development of a scaled-up tidal energy facility around Semakau Landfill and St. John’s Island, which will then be integrated with the first phase.

A key long term goal of the initiative is the development of microgrid technologies that can help provide electricity to overseas communities that do not have access to power. This is in addition to introducing new technologies that can stabilize power grids in urban communities. Both are widely regarded as critical needs across Asia.